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https://issues.apache.org/jira/browse/HADOOP-1986?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12536254
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Doug Cutting commented on HADOOP-1986:
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I don't see the need for 'acceptObjectReference()'. Clients which wish to
reuse objects can, the first time, pass null. For subsequent calls they can
pass the value returned from prior call. This will work well with
implementations which reuse and with implementations that don't, no?
Note also that we don't need an explicit 'accept()' method: if
factory.getSerializer(c) returns null, then that factory does not know how to
serialize instances of the class.
Finally, if we have stateful serializers, then we have to make it clear that
they must not do any buffering. An application should be able to call
'serializer.setOutput(out)', serialize an instance or two, do other,
non-serializer output to 'out', and then serialize more instances, without
calling 'setOutput' again, right? In the case of Writable, setOutput would
just set the protected 'out' field of a DataOutputStream, and this would all
work fine. That could be instead done on each call to a 'serialize(Object,
OutputStream)' method, but perhaps its better to factor it out of inner loops.
Is that the intent?
> Add support for a general serialization mechanism for Map Reduce
> ----------------------------------------------------------------
>
> Key: HADOOP-1986
> URL: https://issues.apache.org/jira/browse/HADOOP-1986
> Project: Hadoop
> Issue Type: New Feature
> Components: mapred
> Reporter: Tom White
> Assignee: Tom White
> Fix For: 0.16.0
>
> Attachments: SerializableWritable.java, serializer-v1.patch
>
>
> Currently Map Reduce programs have to use WritableComparable-Writable
> key-value pairs. While it's possible to write Writable wrappers for other
> serialization frameworks (such as Thrift), this is not very convenient: it
> would be nicer to be able to use arbitrary types directly, without explicit
> wrapping and unwrapping.
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